Where are we with algae biofuels?

October 13, 2014 |

NAABB-close-out-report-synopsisThe state of R&D so far. 4 NAABB advances  have brought the cost of algae biocrude oil down to $7.50 per gallon.

3 roadblocks remain between today’s cost and $3.00.

In our two-part series, we look first at the breakthroughs that have radically changed the costs and outlook. In Part II, we look at where the opportunities lie to reach $2.00 per gallon algae biocrude oil.

If you have been looking for a good survey of algae’s progress towards markets like astaxanthin or omega-3 fatty acids, this isn’t going to be one of them. Here, we look at the prospects for algae biofuels — the roadblocks and the potential pathways forward.

The DOE had studied algae intensively from the late 1970s through the mid-1990s, closing down the Aquatic Species Program in 1996 when oil prices dipped below $20/barrel and it seemed like algae biofuels were too far away to continue the R&D effort.

By 2009, as oil prices reached $100 per barrel, amid rising concerns about domestic energy security and greenhouse gas emissions, the DOE re-embarked in a major way on a voyage in algae biofuels, and issued a “Development of Algal/Advanced Biofuels Consortia” funding opportunity. Eventually, DOE awarded $48.6 million to a consortium of organizations who formed the National Alliance for Advanced Biofuels and BioProducts, the NAABB, with the Donald Danforth Plant Science Center as lead institution and Los Alamos’ Jose Olivares as principal investigator.  The partners contributed $19.1 million in private funds.

They had a three year mission in developing the following pathways: Feedstock Supply–Strain development and cultivation; Feedstock Logistics–Harvesting and extraction; and Conversion/Production–Accumulation of intermediates and synthesis of fuels and co-products.

As a National Research Council report stated in 2012, “sustainable development of algal biofuels would require research, development, and demonstration” in five key areas:

1. Algal strains with enhanced growth characteristics and biofuel productivity;

2. An energy return on investment (EROI) that is comparable to other transportation fuels or at least improving and approaching the EROIs of other transportation fuels;

3. Reactor strategies that use either wastewater for cultivating algae for fuels or recycled water from harvesting systems, particularly if freshwater algae are used;

4. Recycling of nutrients in algal biofuel pathways that require harvesting, unless coproducts are produced that meet an equivalent nutrient need; and

5. A national assessment of land requirements for algae cultivation to inform the potential amount of algal biofuels that could be produced economically in the United States. That assessment must take into account climatic conditions; freshwater, inland and coastal saline water, and wastewater resources; sources of CO2; and land prices.

The NAABB consortium represented an extensive line-up of institutions and enterprises

National Laboratories included the Los Alamos National Laboratory; Pacific Northwest National Laboratory; Idaho National Laboratory; National Renewable Energy Laboratory; and the USDA’s Agricultural Research Service

Universities included Brooklyn College, Clarkson University, Colorado State, Iowa State, Michigan State, New Mexico State, North Carolina State, Texas AgriLife Research / Texas A&M, University of Arizona, UCLA, UC-Riverside, UC-San Diego, Penn, University of Texas, University of Washington, Washington State and Washington University.

Industry partners included Albemarle Catilin, Diversified Energy, Eldorado Biofuels, Genifuel, Cellana, Inventure, Kai BioEnergy, Palmer Labs, Phycal, Reliance Industries, Pan Pacific, Solix Biosystems, Targeted Growth, Terrabon, UOP, Honeywell’s UOP and Valicor.

When NAABB got underway, it established a starting baseline cost of $240 per gallon (for algae biocrude) based on the production, harvest, extraction and upgrade technologies developed to that point. Everyone agreed that the baseline could be radically improved — but how much, how fast.

In a close-out report released this past summer, NAABB noted that the consortium reached a $7.50 per gallon cost for algae biocrude, or an improvement of two orders of magnitude, in its three-years of existence.

The R&D effort was organized into seven areas: “(1) the development of new strains, (2) cultivation processes with these new strains, (3) harvest processing of the algal biomass, (4) extraction processing for crude lipids and LEA, (5) LEA conversion and LEA product trials, (6) direct conversion processes of algal biomass to biocrude, and (7) upgrading lipids and biocrudes to fuels.”

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Let’s look today at the 4 major breakthroughs — and the three major challenges going forward. As NAABB reported, its breakthroughs were:

  1. New strain development—Discovery of a new platform production strain, Chlorella sp. DOE1412, which has the robust ability to produce good oil yield under a variety of conditions. When combined with genetically modified (GMO) versions of the strain the cost of algal biocrude would be reduced by 85%.
  2. Improved cultivation—Development of a new open pond cultivation system, the Aquaculture Raceway Integrated Design (ARID), which uses little energy, extends the growing period, improves productivity, and provides a 16% cost reduction.
  3. Low energy harvesting technology—Demonstrated use of an electrocoagulation (EC) harvesting technology, which is a low-energy, primary harvesting approach using commercially available equipment that provides a 14% cost reduction.
  4. High-yield extraction-conversion technology—Creation of a unique hydrothermal liquefaction (HTL) system that combines extraction and conversion to provide high biocrude yield without the need for extraction solvents, resulting in an 86% cost reduction.

Strains

As NAABB reflected in the close-out: “At the start of the NAABB consortium in 2010, little was known about the molecular basis of algal biomass growth or oil production. Very few algal genome sequences were available and efforts to identify the best producing wild species through bio-prospecting approaches had largely stalled since the efforts of the ASP. Furthermore, algal genetic transformation and metabolic engineering approaches to improve biomass and oil yields were in their infancy.

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So, it would be a two-pronged effort. First, restart the effort to build a library of wild types, and characterize them. Second, use the new biological tools to develop improvements for productivity and oil content.

In all, “approximately 400 samples were collected across the continental United States..and over 2200 independent strains were isolated, and over 1500 of those were subjected to a preliminary screen for oil accumulation. The strains were compared to the NAABB’s benchmark strain, Nannochloropsis salina CCMP1776.

On the engineering front, the NAABB found that “engineering self-adjusting photosynthetic antennae into C. reinhardtii resulted in a significant two-fold increase in biomass accumulation,” and concluded that it the trait could be transported into the Chlorella sp production strain. At the same time, NAABB increased the “Oil accumulation levels…as much as five-fold without affecting growth rates, using a variety of metabolic engineering strategies.”

Summarizing the achievements, principal investigator Jose Olivares told the Digest that “The final analysis combined a genetically modified strain of Chlamydomonas reinhardtii that provided 3x the productivity of the wild type. That modification is being placed into a production strain of Chlorella sorokiniana. The maximum productivity of the Chlorella wild type strain was around 16 g/m2/d. The productivity was modeled depending on season from 50%-200% increase. The actual biomass production rate used in the final analysis to get to $7.50 was 23.2 g/m2/d.”

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Additionally, “NAABB identified antimicrobial peptides that kill bacteria and rotifers without harming algae,” and noted that “We expect that this new class of agents will help to protect algae cultivation ponds against invasion by predators and reduce the loss of crops due to pond crashes.”

Bottom line: NAABB reported an 85 percent increase in algae oil production.

Cultivation

When it comes to improving cultivation, the NAABB had its work cut out for it — as cultivating algae in ponds has been practiced for nearly 50 years, though primarily to make nutritional supplements such as spirulina.

The challenges to productivity in the field are primarily:

1. To extend the algae growing season and broaden the geography.

2. Grow algae with lower-cost inputs, such as wastewater instead of fresh.

3. Improve the cultivation system design to boost yield and drop cost, for example energy costs.

A key advancement that NAABB reported was: ” the modeling, testing, and design improvements of the ARID pond culturing system. The advantage? “Improved temperature management…and engineered reductions in the energy use for pumping and mixing.” ARID, overall, kept water temperatures during the winter in Tucson 7–10°C warmer than in conventional raceways, with “significantly higher annual biomass productivities,” and “significantly higher energy productivity (biomass produced per unit energy input) than conventional raceways.”

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NAABB concluded: “By extending the growing season through modulating temperatures combined with lower energy requirements, the impact of the ARID system could be profound. The ARID system could significantly increase annual biomass productivities with lower operating cost for any microalgae strain of choice.”

Bottom line: NAABB reported a 16% cost reduction.

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Harvesting

As we once observed, a huge challenge in algae is to affordably get the water out of the algae or the algae out of the water — else one is basically in the water business.

NAABB focused on “new harvesting and extraction technologies that would: be easy to integrate with cultivation facilities to limit pumping and power requirements; have low environmental impact; be capable of high volume processing (at least 100– 1000 Liters/hour); and be demonstrated with real-world cultivation samples.”

Overall, NAABB started with five harvesting technologies and ended up with three:

Ultrasonic harvesting, a process applying a standing acoustic wave in a flow-through system to gently aggregate algal cells, thereby facilitating sedimentation out of the cultivation media; Cross-flow membrane filtration, a process using novel ceramic-coated membrane sheets with pore structures and surface properties engineered for algal harvesting; and Electrocoagulation or electrolytic aggregation, a process applying a charge to algal cells forcing them to aggregate and sediment”

NAABB reported that “all three NAABB harvesting technologies showed promise as primary harvesting techniques,” but focused on the electrocoagulation process traditionally used for wastewater treatment, where field tests achieved a 50X concentration factor and 95% recovery of algae using only 25% of the energy used by the baseline centrifuge technology.

Bottom line: NAABB reported a 14% cost reduction

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Extraction & Conversion

It would be in extraction where NAABB would report perhaps its biggest breakthrough, in what the consortium reported as “the development and demonstration of a combined HTL-CHG process that uses algae concentrated from the pond.”

That’s “hydrothermal liquefaction” and “catalytic hydrothermal gasification”, to those who prefer their acronyms decoded.

NAABB explains: “Wet algal biomass (15 -20% solids) is fed directly to the HTL system, which produces bio-oil and an effluent water stream that phase separates without the need of solvent extraction. Th e bio-oil stream is readily upgraded via hydrotreating to hydrocarbon fuel. Th e hydrotreated oil can then be fractionated into jet, diesel, and naphtha fractions. The effl  water stream is then processed with CHG to recover additional fuel in the form of a methane gas/carbon dioxide mixture, and the water stream.”

The result? A biocrude ready for upgrade to hydrocarbon fuels. The consortium reported that this process resulted in the most oil, the best economics and the best lifecycle assessment on greenhouse gas emissions.

As NAABB noted: “advantages of the HTL-CHG processing pathway include: (1) capture of 85% of the carbon in algae as fuel-grade components (bio-oil that can be upgraded to diesel, jet, gasoline, and syngas); (2) production of a bio-oil that can be readily converted to meet diesel and Jet A fuel standards; (3) effective wastewater treatment to reduce the organic content and provide methane for process energy; (4) recycle of water and nutrients (nitrogen, phosphorous, and other trace minerals for algal cultivation; and (5) significant decrease in capital and operating costs compared to processes requiring high lipid-yielding algal biomass and extraction of the lipid from the biomass.

Bottom line: NAABB reported an 86% cost reduction.

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But what about all that extra biomass — isn’t there real value in the fishmeal market, for example?

Not according to NAABB. In looking at co-product value for the lipid-extracted algae, they found that the drivers of value were: “Organic matter—The organic matter content ranged from 40% to 76%; Crude protein—The protein content ranged from 12% to 38%; Residual lipid—The residual lipid content ranged from 1% to 10%.  Mineral content—The presence of heavy metals in the water supply or significantly impact the mineral profile of the LEA, with potential impact in palatability and toxicity.”

Overall, the values were low. “NAABB valued LEA as a feed supplement for animals at $160/ton and for mariculture at $200/ton. Whole algae for mariculture was valued at closer to $400/ton.” Which offsets the cost of the algae biocrude oil something like $0.80 per gallon, if 50% of the biomass represents the lipid-extracted algae.

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The Bottom Line, to date

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Put them all together and you get from $240 to $7.50 for algae biocrude oil. Now, that’s probably a viable cost in some remote location where fuel has to be shipped in, but it’s not ready for prime time. We’ll take up the pathway from $7.50 to $3.00 in Part II, tomorrow.

You can also read the NAABB report here.

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